how does the flow of energy move through a food chain.please give an answer that is good for a grade 9 student

A food chain or a food web is a way to trace energy
through an ecosystem. For most ecosystems (deep ocean vents being the exception),
sunlight is the source of energy. The sunlight is captured through photosynthesis in the
cells of plants, which are primary producers. The plants are eaten by herbivores, which
are primary consumers (examples: insects, deer, squirrels). The primary consumers are
eaten by secondary consumers (insect-eating birds, weasels, bobcats). Tertiary consumers
eat secondary consumers; these are usually the top carnivores, such as hawks and
wolves.Saprobes and detritivores eat dead organic materials and recycle nutrients back
into the soil - these would be things like worms, maggots, and
fungi.

At each step along the way some of the energy is
lost as heat, so the sun's input is needed to keep the web supplied with new energy all
the time.